The fourth season of The Crown, which will be released on November 15, will cover the rifts and romances of the Royal Family between 1977 and 1990. During that time, Lord Mountbatten, the Queen's cousin, was assassinated.
At the end of the 1970s, the Royal Family were absorbed with safeguarding their line of succession to the British throne, trying to find an appropriate bride for Prince Charles who remained unmarried at the age 30.
When Lord Mountbatten was assassinated, Prince Charles had lost his mentor.
In the wake of his grief, Charles formed a relationship with Diana Spencer, who he went on to marry in 1981.
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Here's everything you need to know about the assassination of Lord Mountbatten.
How did Lord Mountbatten die?
After days of rain, the sun was shining. On August 27, 1979, Lord Louis Mountbatten was staying at his holiday home, Classiebawn Castle in Ireland, when he decided to take his fishing boat out with his family.
Affectionately known as "Lord Dickie" by his fellow members of the Royal Family, Lord Mountbatten was a 79-year-old World War II hero and the second cousin of Queen Elizabeth II.
With him on the boat was his eldest daughter, Patricia, Lady Brabourne; her husband Lord Brabourne; their twin sons Nicholas and Timothy Knatchbull; Lord Brabourne's mother Doreen; and a crew member, Paul Maxwell. It was a crowd of seven.